How much blur in moving water is enough for you? To preserve my realistic take on nature, I dial up the shutter speed to hold water in place. Shooting fast is usually possible without a camera support.

ISO 400, 35mm lens, f2.8 @ 1/1250

Yes, it seems that the “cotton candy” look for moving water is currently in vogue. If that’s the way you like it, dial down the shutter speed and ISO. Then use a small aperture to extend the exposure time. You could use either a neutral-density filter or, in a pinch, a circular polarizing filter which will provide about 2 stops.

ISO 100, 35mm lens, f22 @ 1/4.

The choice on the amount of blur is yours–rather like hot sauce on a burrito. The great part of the decision is that it’s all yours to make.